<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body onload="init()">
    <h1 style="text-align: center" id="hmsg">请先登录系统</h1>
    <div><a href="#">去登陆</a></div>
<script>
    function init() {
        let msg = location.search;
        if(msg){
            msg = decodeURI(msg);
            hmsg.innerHTML = msg.substring(1);
        }
    }
</script>
</body>
</html>